On Windows, use c++20 mode as correctly needed for designated initial…

…izers.

Designated initializers is technically only supported starting with c++20,
and the compiler on Windows points that out with an error.

.bazelrc

@@ -21,7 +21,8 @@ common:macos --features=-supports_dynamic_linker --linkopt=-framework --linkopt=
 # Force the use clang-cl on Windows instead of MSVC. MSVC has some issues with
 # the codebase, so we focus the effort for now is to have a Windows Verible
 # compiled with clang-cl before fixing the issues unique to MSVC.
-common:windows --compiler=clang-cl --cxxopt=/std:c++17 --host_cxxopt=/std:c++17 --client_env=BAZEL_CXXOPTS=/std:c++17
+# Since we use designated initializers (C99 ... but >= c++20), compiler really wants the c++20 mode
+common:windows --compiler=clang-cl --cxxopt=/std:c++20 --host_cxxopt=/std:c++20 --client_env=BAZEL_CXXOPTS=/std:c++20
 
 # Address sanitizer settings.
 build:asan --strip=never

.github/workflows/verible-ci.yml

@@ -500,17 +500,20 @@ jobs:
         restore-keys: bazelcache_windows2_
 
     - name: Install dependencies
-      # Bazel breaks on Windows with LLVM 16. Will be fixed in bazel 6.4
-      run: choco install llvm --force --version=15.0.7
+      run: |
+        choco install bazel --force --version=6.4.0
+        choco install llvm --force
+	choco list -lo
+	BAZEL_BIN=C:/ProgramData/chocolatey/lib/bazel/bazel.exe
 
     - name: Debug bazel directory settings
-      run: bazel info
+      run: $BAZEL_BIN info
 
     - name: Run Tests
-      run: bazel test --keep_going --noshow_progress --test_output=errors //...
+      run: bazel-6 test --keep_going --noshow_progress --test_output=errors //...
 
     - name: Build Verible Binaries
-      run: bazel build --keep_going --noshow_progress -c opt :install-binaries
+      run: bazel-6 build --keep_going --noshow_progress -c opt :install-binaries
 
     - name: Prepare release
       run: |